Some Muslims believe that Dhul-qarnain or Zul-qarnain
is the Persian King Cyrus:

Please be advised that I disagree with the author for claiming
that Alexander was a Pagan. According to the historical references in the Gog and Magog and the Iron Gates article, Alexander was considered a great person to the Jews and is
considered like a Saint for the Christians, even though he existed before Jesus peace be
upon him. His importance to both Jews and Christians eliminates the (perhaps false)
fact that he was an idol worshiper.

Let us continue with the article:

The following article was sent to me by brother Mark; may Allah Almighty always be pleased with him.

Gog and Magog:

Hello, and God's blessings upon you. With all due respect to your beliefs, you
are mistaken 'Zhulkarnein' of the holy Koran is NOT Alexander the Great. It is Cyrus
the Great, the famous Persian king of the Achamenid Dynasty (600?-541 B.C). Consider
the following:

1- Alexander was not a monotheistic man. He was a blasphemer who worshipped the
many gods of Ancient Greece. The Biography of Alexander, written by a famous Greek
historian (Herodotus?) states that Alexander believed that he was the son of Zeus!
This contradicts the Koran, which states that Zhulkarnein was a man of Godly faith.
Also, Alexander was a lecherous womanizer of the worst kind, and was far from what you
would call a gentleman (inspite of his military genius). He killed one of his
generals in a drunken frenzy.

My personal objection to this point:
As I mentioned above, Alexander is considered as a great person to the Jews and is
like a Saint to the Christians. There is no proof that he was a Pagan. Also,
regarding the "Womanizer" point, well, according to Islam, we believe in the
Prophets of the Bible peace be upon all of them. They too were
"Womanizers" if you wish to use this term, for many of them had literally
hundreds of wives from all ages.

2- The Koranic verses in the 'AL KAHF' sura, which talk about Zhulkarnein, begin with
the words: "And they ask you about Zhulkarnein..".
Meaning that the Jews are asking the Prophet Muhammad about him. This means
that this king was KNOWN TO THE JEWS, AND IS MENTIONED IN THE OLD TESTAMENT.
Alexander the Great is not mentioned in the Old Testament, nor did he have any close
relation with the Jews.

3-The word "qarn" in the Koran has one meaning and one meaning only: It
means: People or Nation. Thus, he was called Zhulkarnein because he was a king of
two peoples or two nations. Historically, Cyrus was of the Achamenid Dynasty, a
dynasty of double throne. He was King of both the Medians and the Persians! He
was the one who overthrew the Babylonian empire and permitted the captive Jews to return
to their homeland and to rebuild their Temple. Thus, the Jews greatly revere and
respect him.

My personal objection to this point:
With all due respect dear brother Mark, but "qarn" in Arabic doesn't mean
people or nation, and "Zhulkarnein" or "Dhul-qarnain" or
"Zul-qarnain" doesn't mean the king of two peoples or two nations either.
"qarn" in Arabic has two meanings: "horn" and
"century". "Dhul-qarnain" could literally mean in Arabic:
"The man of two horns" or "The man of two centuries". This
"one word having multiple meanings" problem if you will, exists in English as
well. Take for instance the word "trunk": It could mean the back of
your car, and it could also mean the trunk of the Elephant.

4- It is Known that Cyrus' empire stretched for the western shores of Turkey in the
west, to the flat and barren deserts near Northern India in the east (you may check any
Encyclopedia to verify this). Also, the Northernmost boundaries of his empire are
the Caucasus mountains, in present day Georgia. The region is full of Ancient
Persian ruins of military fortifications and strongholds.

5- Geographically, the Caucasus mountains form a natural and almost impassable barrier
that stood between the civilized kingdoms of central Asia, and the northern plain lands
were the savage barbarian and nomadic tribes once roamed. Among the only natural
passes through these formidable mountains is a stretch of open ground known today as
"Daryal Pass". It is located north of Tiblisi, the capital of Georgia.
The area is called: "doorway of Ghurash" (Ghurash is Armenian for Cyrus).
The remains of a metallic rampart STILL STAND TODAY, as part of ancient Persian
fortifications.

6- The technique used by Cyrus in building this 'wall' was not known to the people of
the region way back then. (He received this technique from God himself!).
Also, the great Greek historian Herodotus states, in his chronicles, that the Georgians
were the first people in the world to have learned how to 'smelt iron'.....(strange
coincidence, eh?).